How do you find all the values that make the expression undefined: #(5x - 25)/(x^2 - 25)#? Algebra Rational Equations and Functions Excluded Values for Rational Expressions 1 Answer George C. May 21, 2015 The values of #x# that make this expression undefined are those for which the denominator (bottom) is zero. #x^2-25 = 0# has solutions #x=+-5# Answer link Related questions How do you find the excluded values of #\frac{2x+1}{x^2-x-6}#? What are Excluded Values for Rational Expressions? How do you state the excluded values for rational expressions? How do you find excluded values for rational expressions? How do you simplify the expression and find the excluded values for the rational expression... How do you simplify rational expressions? Can you use long division to simplify rational expressions? How do you simplify #\frac{x-2}{x^2-4x+4}#? What is the excluded value of #\frac{2x-1}{(x-1)^2}#? How do you write #(z^3-8)/(z^2+2z+4)# in simplest form? See all questions in Excluded Values for Rational Expressions Impact of this question 1881 views around the world You can reuse this answer Creative Commons License